The efficacy of treatment of erythrasma with an antibacterial bar soap was determined in two double-blind studies. In one, subjects lathered twice daily for 21 days; infected areas showed 75% to 100% resolution at the end of three weeks. In a second group, 2,600 subjects used the test soap or a placebo bar exclusively for the daily bath for two months. Seventy of these subjects had erythrasma. In the group using the antibacterial bar soap, infected areas all resolved, whereas infection in the control group was essentially unchanged.
Dodge BG, Knowles WR, McBride ME, Duncan WC, Knox JM. Treatment of Erythrasma With an Antibacterial Soap. Arch Dermatol. 1968;97(5):548-552. doi:10.1001/archderm.1968.01610110056010